Rigid foam panels have been in wide use since the oil crisis of the early 1970's. Whether for exterior or interior use, rigid foam panels have provided an additional layer of insulation for houses and commercial buildings that, before the energy crisis, were often uninsulated, or insulated with fiberglass batting.
As with any new technology, rigid foam panels have been refined over the years. Originally, the panels were used as a replacement for fiberglass batting, and were cut to fit between studs. Later, sheets of rigid foam were used on the sides of houses being remodeled to add additional insulation to the exterior walls.
One continuing problem with the use of rigid foam panels has been their fragility as compared to other building materials, such as wood, steel, fiberglass and the like. The panels have limited tensile strength, and therefore cannot be used by themselves to support a great deal of weight on small connectors, such as nails and screws. Furthermore, the forces needed to attach nails and screws to a wall or ceiling of a house or commercial building when doing original construction or repair can quite easily damage the foam panels during installation.
When foam panels are used to form an insulated sheath around a wall that is being constructed, remodeled, or repaired, some of the most difficult issues are how to attach the foam panels. Since they are easily crushed, they cannot be used as an outer  surface covering by themselves, or with a coat of paint, for example. As a result, some environmentally hardened wall covering must be applied over them, such as shingles, shakes, wallboard, and wood or other paneling.
When rigid foam insulation is applied it must therefore permit or provide for an additional layer to be attached to it, or at least be in contact with its outer surface. This problem is not a trivial one to solve, especially for interior walls in which another relatively fragile material, gypsum board, is attached. One cannot easily, and in many cases may not wish to attach the layer of wall covering directly to the wall or studs behind the rigid foam paneling. For example, when attaching interior wall covering to a concrete wall, particularly an exterior concrete wall, it is especially bad to have fasteners such as nails or screws penetrating the wall-covering passing through the rigid foam layer, and being embedded in the concrete wall. Such fasteners provide a simple channel for heat loss and for vapor or water penetration to the outer surface of the wall covering.
My co-pending application entitled “An Insulated Concrete Wall System And Method For Its Manufacture”, filed contemporaneously with this application, describes a concrete wall system using the rigid foam panel described herein, and is incorporated by reference in this application for methods of using the panel, ways of constructing the panel, the structure and features of the panel, and all other teachings.
Another disadvantage to plain rigid foam sheets is their tendency to obscure the location of appropriate hanging points for the wall coverings that are subsequently attached through them to a wall. For example, once a complete sheet of rigid foam is attached to a wall, the trusses, and framing to which they were attached is completely covered up. When the subsequent layer of wall covering, such as siding or wallboard is attached, it is difficult, if not impossible to identify the location of the studs or trusses to which the foam was attached, and to which the wall covering must be attached as well. The only way to identify the location of the studs is with such tools as “stud finders”, special electronic devices that can be waved in front of the wallboard to find the location of a good mounting point for the wall covering, such as the underlying studs or trusses. These devices are notoriously unreliable, sensing as they do, the presence of a stud by capacitive or inductive means. In addition, their use  requires a separate hand to move the stud finder back and forth across the front of the wall covering until a “beep” is heard or a small red light flashes. All of this happens because the rigid foam covers up the mounting locations for mounting the subsequent wall-covering layer.
What is needed is a modified rigid foam panel and an efficient method of manufacturing it that avoids some, if not all of these problems (depending upon the embodiment). It is an object of this application to provide such a panel.